Complex ion is shown by

Which of the following is paramagnetic

All the following statements about the transitional elements are true except that

Effective magnetic moment of $S{c^{ + 3}}$ ion is

For the ions $Zn ^{2+}, \,Ni ^{2+}$ and $Cr ^{3+}$ which among the following statements is correct ?

(Atomic number of $Zn =30,\,Ni =28$ and $Cr =24$ )

The stability of $Cu ^{2+}$ is more than $Cu ^{+}$salts in aqueous solution due to -